Method for the production of metal complexes

ABSTRACT

The invention relates to a process for preparing metal complexes containing carbene ligands by reacting metal compounds with ligand precursors II and/or III and to the use of the thus obtained metal complexes as catalysts.

The invention relates to a process for preparing metal complexescontaining carbene ligands by reacting metal compounds with ligandprecursors II and/or III and to the use of the thus obtained metalcomplexes as catalysts.

Metal complexes which contain, as the central atom, a metal of groups 6to 10 of the Periodic Table of the Elements and ligands bonded to thismetal atom are increasingly being used as catalysts for chemicalreactions. Their significance lies in particular in reactions which leadto the formation of carbon-carbon, carbon-hydrogen, carbon-oxygen andcarbon-nitrogen bonds. Often, metal complex catalysts are used inindustrial processes. Examples of such processes are thehydroformylation of olefins, the hydrogenation of olefins, aldehydes orketones, for example, metathesis reaction and telomerization.

The ligands which coordinate to the metal atom have an immense influenceon the catalytic behavior of the metal complex. Firstly, they exert astabilizing effect, which is why they are often even used in excess incatalytic reactions. Secondly, activity and selectivity of the catalystare controllable within a wide range via the type of ligands.

The ligands used are mainly nitrogen compounds, for example amines, orphosphorus(III) compounds, for example phosphines or phosphites. For thetelomerization of 1,3-butadiene with methanol, in which mainly2,7-octadienyl methyl ether is formed, in EP 0 461 222, for example,triphenylphosphine is described as the ligand and palladium as the metalof groups 6-10.

In recent times, N-heterocyclic carbenes are additionally increasinglyfinding use as ligands in metal complexes. The use of these ligandsallows sometimes considerable advantages to be achieved over catalystswhich contain only phosphorus ligands. Various possible uses andexamples of the use of the N-heterocyclic carbenes as ligands can befound in reviews which document the current state of the art (W. A.Herrmann, Angewandte Chemie 2002, 114, 1342-1363; W. A. Herrmann, T.Weskamp, V. P. W. Böhm, Advances in Organometallic Chemistry, 2001, Vol.48, page 1-69; L. Jafarpour, S. P. Nolan, Adv. Organomet. Chem. 2001,46, 181; D. Bourissou, O. Guerret, F. P. Gabbai, G. Bertrand, Chem. Rev.100, 39).

The use of an N-heterocyclic carbene as a ligand in a palladium complexwhich is used as a catalyst for the telomerization of 1,3-butadiene withmethanol is likewise described (R. Jackstell, M. Gómez Andreu, A.Frisch, K. Selvakumar, A. Zapf, H. Klein, A. Spannenberg, D. Röttger, O.Briel, R. Karch, M. Beller, Angewandte Chemie 2002, 114, 128). Here too,distinct improvements over catalyst systems having phosphorus ligandscan be demonstrated.

The successes which have been achieved with the N-heterocyclic carbenesas ligands show that individual catalytic problems can be solved withnovel metal complexes as catalysts. At the same time, it is necessarythat metal complexes which are used as catalysts are obtainable simplyand inexpensively.

It is therefore an object of the present invention to provide a processfor preparing the metal complexes.

The present invention therefore provides a process A process forpreparing complexes of metals of groups 6 to 10 of the Periodic Table ofthe Elements by reacting a compound of a metal of groups 6 to 10 of thePeriodic Table of the Elements with compounds of the formula II and/orIII

where

-   -   R¹, R², R³, R⁴ are the same or different and are each linear,        branched, substituted or unsubstituted, cyclic or alicyclic        alkyl groups having from 1 to 24 carbon atoms; substituted or        unsubstituted, mono- or polycyclic aryl groups having from 6 to        24 carbon atoms; mono- or polycyclic, substituted or        unsubstituted heterocycles having from 2 to 24 carbon atoms; a        heteroatom from the group of N, O, S, and R³, R⁴ may have a        covalent bond    -   R⁵, R⁶, R⁷ may be the same or different and may each be H,        linear, branched, substituted or unsubstituted, cyclic or        alicyclic alkyl groups having from 1 to 24 carbon atoms;        substituted or unsubstituted, mono- or polycyclic aryl groups        having from 6 to 24 carbon atoms, with the proviso that the R⁷        substituent is not H.

When the ligand precursors used are ionic compounds, they are used as asalt with the counterion [Y⁻].

[Y⁻] is preferably halide, pseudohalide, tetraphenylborate,tetrafluoroborate, tetrachloroborate, hexafluorophosphate,hexafluoroantimonate, tetracarbonylcobaltate, hexafluoroferrate,tetrachloroferrate, tetrachloroaluminate, triflate,bistrifluorosulfonylamide, heptachlorodialuminate, tetrachloropalladate,sulfate, hydrogensulfate, nitrate, nitrite, phosphate,hydrogenphosphate, dihydrogenphosphate, hydroxide, carbonate,hydrogencarbonate, salts of aromatic or aliphatic carboxylic acids,salts of aromatic or aliphatic sulfonic acids or phenoxides.

R⁵, R⁶, R⁷ may have the same definitions or, for example, be substitutedor unsubstituted aryl-, heteroaryl-, alkyl-, alkenyl-, allyl group, —CN,—COOH, —COO-alkyl-, —COO-Aryl-, —OCO-alkyl-, —OCO-aryl-, —OCOO-alkyl-,—OCOO-aryl-, —CHO, —CO-alkyl-, —CO-aryl-, —O-alkyl-, —O-aryl-, —NH₂,—NH(alkyl)-, —N(alkyl)₂—, —NH(aryl)-, —N(aryl)₂—, —F, —Cl, —Br, —I, —OH,—CF₃, —NO₂, -ferrocenyl, —SO₃H, —PO₃H₂, where the alkyl groups containfrom 1 to 24, the alkenyl and heteroaryl groups from 2 to 24 and thearyl groups from 5 to 24, carbon atoms. In the process according to theinvention, preference is given to using ligand precursors which satisfyone of the general formulae (V) to (X):

where R¹, R², R⁵, R⁶ and R⁷ are each as defined above and R⁸, R⁹, R¹⁰and R¹¹ may be the same or different and each be hydrogen or have one ofthe definitions of R¹.

R⁸, R⁹, R¹⁰, R¹¹ are preferably the same or different and are eachhydrogen, substituted or unsubstituted aryl-, heteroaryl-, alkyl-,alkenyl-, allyl group, —CN, —COOH, —COO-alkyl-, —COO-aryl-, —OCO-alkyl-,—OCO-aryl-, —OCOO-alkyl-, —OCOO-aryl-, —CHO, —CO-alkyl-, —CO-aryl-,—O-alkyl-, —O-aryl-, —NH₂, —NH(alkyl)-, —N(aryl)₂—, —NH(aryl)-,—N(alkyl)₂—, —F, —Cl, —Br, —I, —OH, —CF₃, —NO₂, -ferrocenyl, —SO₃H,—PO₃H₂, where the alkyl groups contain from 1 to 24, the alkenyl andheteroaryl groups from 2 to 24 and the aryl groups from 5 to 24, carbonatoms, and where the R⁸ and R⁹ radicals may also be covalently joined.

The R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹ radicals may be thesame or different and each have a substituent from the group of —H, —CN,—COOH, —COO-alkyl, —COO-aryl, —OCO-alkyl, —OCO-aryl, —OCOO-alkyl,—OCOO-aryl, —CHO, —CO-alkyl, —CO-aryl, -aryl, -heteroaryl, -alkyl,-alkenyl, -allyl, —O-alkyl, —O-aryl, —NH₂, —NH(alkyl), —N(alkyl)₂,—NH(aryl), —N(alkyl)₂, —F, —Cl, —Br, -1, —OH, —CF₃, —NO₂, -ferrocenyl,—SO₃H, —PO₃H₂, where the alkyl groups contain from 1 to 24, the alkenyland heteroaryl groups from 2 to 24 and the aryl groups from 5 to 24,carbon atoms.

Substituents having acidic hydrogen atoms may also have metal orammonium ions instead of the protons.

R¹ and R² may each be the same or different and are in particularisopropyl, tert-butyl, adamantyl, cyclohexyl, benzyl, phenyl,substituted phenyl radicals (for example mesityl, tolyl, xylyl,2,6-diisopropylphenyl, p-methoxyphenyl, 2,3-dimethoxyphenyl,p-chlorophenyl and mono- or polycyclic rings which contain at least oneheteroatom).

These are, for example, radicals which derive from five- andsix-membered heteroalkanes, heteroalkenes and heteroaromatics such as1,4-dioxane, morpholine, y-pyran, pyridine, pyrimidine, pyrazine,pyrrole, furan, thiophene, pyrazole, imidazole, thiazole and oxazole.

R⁸, R⁹, R¹⁰ and R¹¹ may each be the same or different and are inparticular hydrogen, methyl, ethyl, phenyl.

In the general formulae (VI) and (IX), the R⁸ and R⁹ radicals areadditionally together a bridging group in which the substituents arejoined together via a covalent bond, and are in particular groups suchas —CH═CH—CH═CH— which lead to the formation of a fused aromatic whichmay optionally be mono- or polysubstituted by the substituentsmentioned.

R⁵, R⁶, R⁷ may each be the same or different and are in particularhydrogen, aryl, heteroaryl or alkenyl substituents. Preferably, one ofthe R⁵ or R⁶ radicals is hydrogen, the other an aryl, heteroaryl oralkenyl substituent. Preferred aryl substituents are substituted orunsubstituted phenyl groups; preferred heteroaryl substituents aresubstituted or unsubstituted pyridyl groups.

The R⁵ and R⁶ radicals are additionally together a bridging group inwhich the substituents are joined together via a covalent bond. Thispreferably forms a five-, six-, seven-membered ring.

The R¹ and R⁵ radicals may additionally together be a bridging group inwhich the substituents are joined together via a covalent bond. Togetherwith the N—C═C unit of the compounds III to VIII, this preferably formsa five-, six-, seven-, eight-, nine- or ten-membered ring. When, forexample, the R¹ and R⁷ radicals together are the —CH₂—CH₂—CH₂— group, asix-membered cycle is formed.

In the process according to the invention, no compounds of the forms IIand/or III are used in which the R³ and R⁴ radicals, and the R⁵ and R⁶radicals, simultaneously contain two nitrogen atoms and are bridged.

Thus, all tetraaminoethylene derivatives of the general formula

do not form part of the subject matter of the process according to theinvention.

The table which follows reproduces examples of ligand precursors used inaccordance with the invention.

The ligand precursors according to the general formulae (II) to (X) maybe prepared synthetically in a simple manner by various routes. Thecompounds (V) to (VII) may, for example, as known from the literature,be obtained by deprotonating the salts (VIII) to (X) in which R⁷ ishydrogen (Liebigs Ann. Chem. 1993, 1149-1151; Chem. Ber. 1987, 120,2053).

For the compounds (VIII) to (X), various synthetic routes likewise seeopen; four are illustrated here by way of example.Synthetic Route 1)

From imidazolium salts, compounds according to the general formula IXmay be obtained by deprotonation and subsequent reaction with alkylhalides (cf. Tetrahedron 1988, 44, 7413).

Synthetic Route 2)

Thiolate groups in the 2-position of imidazolium salts may be exchangedby nucleophilic substitution reactions (Liebigs Ann. Chem. 1993,1149-1151).

Synthetic Route 3)

Imidazolium salts of the general formula (IX) are accessible viaassembly reactions from α-dicarbonyl compounds, primary amines andaldehyde (WO 91/14678).

Instead of a one-stage synthesis, a 1,4-diazabutadiene can first beformed from the α-dicarbonyl compound and the amine and then reactedwith aldehyde.

The compounds of the type (VIII) are accessible by reacting 1,2-diamineswith orthoesters. As an alternative to the orthoesters, nitriles mayoptionally be used (J. Med. Chem. 1977, 20, 531).

Synthetic Route 4)

Synthesis by quaternization of the nitrogen atom in substitutedimidazoles, for example using alkyl halides as the alkylating agent.

The process according to the invention introduces N-heterocyclic ligandsinto metal complexes. This can be done with extension of the ligandsphere or with displacement of one or more ligands already present inthe metal compound (I) or (XI).

The introduction of the carbene ligand may also be accompanied by theintroduction of additional new ligands, by a ligand exchange or by achange in the coordination of ligands already present. This process isnot unusual and is also observed in the preparation of metal-carbenecomplexes via other synthetic routes; cf. EP 0 721 953 B1.

According to literature processes, N-heterocyclic carbene ligands areintroduced into metal complexes mainly via three routes: a) by reactingmetal compounds with the free N-heterocyclic carbenes, b) by in situdeprotonation of ligand precursors to form the free carbenes, c) bycleaving dimers of carbenes (W. A. Herrmann, T. Weskamp, V. P. W. Böhm,Advances in Organometallic Chemistry, 2001, Vol. 48, page 1-69). Thefree N-heterocyclic carbenes are often only of limited stability or canonly be handled in solution.

The process according to the invention opens up a new route to the metalcomplexes which uses ligand precursors which are simple to prepare andstable. In the literature, there are to date no experimentaldescriptions of this reaction. For the addition of imidazolium saltshaving hydrogen or halogen substituents on metals of group 10, examplesare known. For the formation of compounds according to the generalformula IX where R⁵═R⁶═R⁷═H from metal carbene complexes too, there areexperimental reports (cf. J. Am. Chem. Soc. 2001, 123, 8317). The samereference also cites calculations on the addition of1,2,3-trimethylimidazolium salts (formula IX where R1 ═R2=methyl,R⁵═R⁶═R⁷═R⁸═R⁹═H) to model complexes of metals of group 10 in the 0oxidation state, but without being able to confirm them withexperimental studies.

WO 02/34722 discloses 1,2,3-substituted imidazolium salts as ionicliquids and the use thereof as solvents, particularly for biphasicreactions. Preference is given to the use as a solvent in particular inreactions in which metal complexes catalyze the reaction. A reaction ofthe metal compounds with the imidazolium salts is neither described normentioned.

As metal compounds of groups 6-10 of the Periodic Table, preference isgiven to using Ru, Rh, Ni, Pd or Pt. Useful compounds are in particularsalts or complexes of the metals. The compounds may contain anionic,cationic or uncharged ligands. Examples of ligands are halides,phosphines, phosphites, phosphonites, phosphinites, amines, nitriles,isonitriles, carbon monoxide, nitrogen monoxide, alkoxides,carboxylates, alkyl substituents, aryl substituents, alkenes, alkynes,aromatics which coordinate via the π-system, such as benzene,cyclopentadienyl, indenyl, carbene ligands (for example Fischer-type,Schrock-type or heterocyclic carbene ligands).

Preference is given to salts or complexes which are obtainable in asimple manner and often commercially available, for example metalhalides, metal acetates, metal acetylacetonates, metal carbonyls.

Suitable metal compounds are, for example:

Palladium compounds:

-   palladium(II) acetate, palladium(II) chloride, palladium(II)    bromide, lithium tetrachloro-palladate, palladium(II)    acetylacetonate, palladium(0)-dibenzylideneacetone complexes,    palladium(II) propionate, bis(acetonitrile)palladium(II) chloride,    bis(triphenyl-phosphane)palladium(II) dichloride,    bis(benzonitrile)palladium(II) chloride,    bis(tri-o-tolylphosphine)palladium(0), allylpalladium chloride    (dimer), bis(tricyclohexylphosphine)—palladium(0).

Platinum compounds:

-   dichloro(1,5-cyclopentadiene)platinum(II),    dichlorobis(benzonitrile)platinum(II),    dichlorobis(pyridine)platinum(I), dichlorodi(ethylene)platinum(II)    dimer, platinum(II) acetylacetonate, platinum(II) chloride,    platinum(IV) chloride, tetrakis(triphenylphosphine)platinum(0),    chloroplatinic acid, potassium hexachloroplatinate(IV), sodium    hexachloroplatinate(IV).

Ruthenium compounds:

-   dichloro(benzene)ruthenium(II) dimer, dichloro(cymene)ruthenium(II)    dimer, dichlorotris(triphenylphosphine)ruthenium(II),    dichloro(1,5-cyclooctadiene)ruthenium(II), ruthenium carbonyls,    ruthenium chlorides, ruthenium(III) acetylacetonate.

Nickel compounds:

-   bis(1,5-cyclopentadiene)nickel(0), bis(triphenylphosphine)nickel(II)    chloride, bis(triphenylphosphine)nickel dicarbonyl, nickel    tetracarbonyl, nickel(II) acetate, nickel(II) acetylacetonate,    nickel(II) chloride, nickel(II) 2-ethylhexanoate, nickel(II)    sulfate, nickel(II) nitrate.

Rhodium compounds:

-   rhodium carbonyls such as tetrarhodium dodecacarbonyl, hexarhodium    hexadecacarbonyl; rhodium dicarbonyl acetylacetonate, rhodium    nitrate, rhodium chloride, Rh(CO)₂(acac) (acac=acetylacetonate),    rhodium formate, rhodium acetate, rhodium octanoate, rhodium    nonanoate, μ-μ-′-dichlororhodium tetracarbonyl, [Rh(OAc)(COD)]₂    (Ac=acetyl group, COD=1,5-cyclooctadiene),    tris(triphenylphosphine)rhodium chloride.

In the process according to the invention, preference is given topreparing complexes of the general formula (I)

where [Z] is a metal complex fragment of the general formula[L_(a)M_(b)][A]_(n)  (XI)and

-   M is: metals of groups 6 to 10 of the Periodic Table of the Elements-   L is: one or more identical or different mono- or polydentate,    charged or uncharged ligands-   A is: a singly charged anion or the chemical equivalent of a    multiply charged anion,-   b is: an integer of from 1 to 3-   a is: an integer of from 0 to 5×b-   n is: an integer from 0 to 6-   and R¹, R², R³, R⁴ are each defined as specified.

Mono- or polydentate ligands which may be present in addition to thecarbene ligand introduced in accordance with the invention in the metalcomplex fragment L are represented by L in the general formula (XI).

L is hydrogen, the hydrogen ion, halogens, halogen ions, pseudohalides,carboxylate ions, sulfonate ions, amide radicals, alkyl groups,alkylaryl groups, aryl groups, heteroaryl groups, alkenyl groups,alkoxide radicals, nitriles, isonitriles, mono- or diolefins, alkynes,π-aromatic radicals, cyclopentadienyl, indenyl, phosphines, phosphites,phosphinites, phosphonites, phosphorus aromatics, acetylacetonate,carbon monoxide, nitrogen monoxide or carbene ligands,

-   where the alkyl groups contain from 1 to 24, the alkenyl and    heteroaryl groups from 2 to 24, and the aryl groups from 5 to 24,    carbon atoms, and may each be substituted or unsubstituted. When a    plurality of L ligands are present, they may be the same or    different.

In the general formula (XI), A is halide, pseudohalide,tetraphenylborate, tetrafluoroborate, tetrachloroborate,hexafluorophosphate, hexafluoroantimonate, tetracarbonylcobaltate,hexafluoroferrate, tetrachloroferrate, tetrachloroaluminate, triflate,bistrifluorosulfonylamide, heptachlorodialuminate, tetrachloropalladate,sulfate, hydrogensulfate, nitrate, nitrite, phosphate,hydrogenphosphate, dihydrogenphosphate, hydroxide, carbonate,hydrogencarbonate, salts of aromatic or aliphatic carboxylic acids,salts of aromatic or aliphatic sulfonic acids and phenoxides.

Preference is given to metal complex fragments according to the generalformula (XI) in which b equals one.

For the preparation of the metal complexes (I), a stoichiometric amountof ligand precursor according to the general formulae (III) to (X) isnecessary. However, when a superstoichiometric amount of ligandprecursor is used, better yields of the compounds (I) are oftenobtained. Typically, the molar ratio of ligand precursor to metalcompound is therefore from 100:1 to 1:1, preferably from 10:1 to 1:1.

The process according to the invention for preparing metal complexes ofthe formula (I) is preferably carried out in the presence of solvents.Suitable solvents include aliphatic, cycloaliphatic and aromatichydrocarbons, for example C₃-C₂₀-alkanes, mixtures of lower alkanes(C₃-C₂₀), cyclohexane, cyclooctane, ethylcyclohexane, alkenes andpolyenes, vinylcyclohexene, 1,3,7-octatriene, the C₄ hydrocarbons fromC₄ cuts from crackers, benzene, toluene and xylene; polar solvents, forexample primary, secondary and tertiary alcohols, di- and polyols(ethylene glycol, diethylene glycol, triethylene glycol, tetraethyleneglycol, polyethylene glycol, glycerol), primary, secondary and tertiaryamines, ammonia, amides, for example acetamide, dimethylacetamide anddimethylformamide, nitriles, for example acetonitrile and benzonitrile,ketones, for example acetone, methyl isobutyl ketone and diethyl ketone;carboxylic esters, for example ethyl acetate, ethers, for exampledipropyl ethers, MTBE, diethyl ether, dimethyl ether, methyl octylether, 3-methoxyoctane, 1-methoxy-2,7-octadiene,3-methoxy-1,7-octadiene, dioxane, tetrahydrofuran, anisole, alkyl andaryl ethers of ethylene glycol, diethylene glycol, triethylene glycol,tetraethylene glycol and polyethylene glycol, and other polar solvents,for example sulfolane, dimethyl sulfoxide, ethylene carbonate, propylenecarbonate and water. Ionic liquids too, for example imidazolium orpyridinium salts, may be used as solvents.

The solvents are used alone or as mixtures of different solvents.

The metal complexes (I) are preferably used as catalysts. It is apreferred embodiment of the process according to the invention togenerate the metal complexes (I) in situ as a catalyst or catalystprecursor. In this case, the solvents utilized are preferably reactantswhich are present in liquid form under the reaction conditions and areconverted in the catalysis. They may, for example, be olefins, halidesor alcohols. These may in turn be used in mixtures with the suitablesolvents already mentioned.

The temperature at which the metal complexes (I) are prepared is from−135° C. to 200° C., preferably from −78° C. to 160° C. The pressure atwhich the metal complexes (I) are prepared is from 1 to 125 bar.

The metal complexes (I) can be prepared in accordance with the inventionin the presence of compounds which can coordinate to metal centers asligands. These include solvents capable of coordination, such astetrahydrofuran or acetonitrile, and compounds which are known asligands suitable for metals. These include, for example, phosphorus(III)compounds such as phosphines, phosphites, phosphinites, phosphinites,phosphabenzenes, nitriles, isonitriles, alkenes, alkynes, dienes,halides, amines.

For the preparation of the metal complexes (I) in the process accordingto the invention, oxidizing or reducing agents may be added to thereaction. The addition of oxidizing or reducing agents allows a change,in some cases additional, in the oxidation state of the metal. Examplesof oxidizing and reducing agents are hydrazine, hydrogen peroxide,formic acid, hydrogen, oxygen, air, stannanes, silanes, alcohols, ionichydrides or amines.

The metal complexes (I) are prepared, depending on the particularsystem, under acidic, neutral or basic conditions. These conditions maybe established appropriately by adding acids, bases or buffers. Theacids used are, for example, mineral acids (sulfuric acid, hydrochloricacid, phosphoric acid), carboxylic acids (formic acid, acetic acid,benzoic acid), sulfonic acids or phenols. Typical bases are, forexample, alkali metal and alkaline earth metal hydroxides, (sodiumhydroxide, calcium hydroxide), alkali metal and alkaline earth metalcarbonates, (sodium carbonate, cesium carbonate), amines, alkoxides andphenoxides (sodium methoxide, potassium t-butoxide, sodium phenoxide),alkali metal and alkaline earth metal hydrides (sodium hydride), andalkyl- or aryl-metal compounds such as butyllithium, butylmagnesiumchloride, phenyllithium.

The metal complexes prepared in accordance with the invention may beisolated in substance and used as a catalyst, or generated in situ andused directly as a catalyst or precatalyst. Precatalyst refers ingeneral and in the context of this invention to a substance, here ametal complex, from which the active catalyst species are formed undercatalysis conditions. This may proceed, for example, with loss of one ormore of the ligands present (for example L in (XI)) and coordination ofthe substrate.

Examples of catalytic reactions in which the metal complexes (I)prepared in accordance with the invention may be used arehydroformylation, hydrogenation, aryl amination, hydrosilylation,carbon-carbon coupling reactions, (for example Heck reaction, Suzukicoupling, Kumada coupling, Stille coupling, Miyaura coupling, theSonogashira coupling), olefin metathesis, olefin dimerization, olefinoligomerization, cyclopropanation, reduction of haloarenes andpolymerization (homo- and copolymerization). It is possible to carry outthe process according to the invention in such a way that the metalcomplexes (I) are formed in situ as a catalyst or precatalyst in theabovementioned reactions.

The present invention therefore provides the abovementioned processeswhich are carried out in the presence of the metal complexes (I), of themetal complexes (I) prepared in accordance with the invention, or of thecompounds II to X as ligand precursors.

Preferred catalytic reactions in which the metal complexes (I) preparedin situ or in substance in accordance with the invention are used as acatalyst or precatalyst are catalytic reactions of olefins or dienes togive olefins or dienes having altered carbon number, in particular themetathesis of olefins and the telomerization of noncyclic, conjugateddienes such as butadiene with alcohols, water or amines.

The molar ratio of one or more of the compounds II to X to the metal ofgroup 6-10 of the Periodic Table is 1:100, in particular 1:10.

The temperature at which catalytic reactions with the complexes preparedby the process according to the invention are carried out, here inparticular the telomerization of butadiene with methanol, is in therange between −78° C. and 200° C., preferably between 20° C. and 160° C.Preference is given to using from 0.00001 mol % to 5 mol % of metalcompound (I) based on the substrate to be converted, particularpreference to amounts between 0.0001 mol % to 1 mol %. Depending on therequirement, acids or bases may be added to the catalytic reaction. Inaddition, further ligands or ligand precursors may be present inaddition to the metal complex (I). Preference is given to using asadditional ligands phosphorus(III) compounds such as phosphines,phosphites, phosphinites, phosphinites and compounds according to thegeneral formulae (II) to (X). The molar ratio of excess ligand to themetal complex (I) is from 500:1 to 0:1, preferably from 100:1 to 0:1,more preferably from 50:1 to 0:1, per ligand.

The catalytic reactions using the metal complexes prepared by theprocess according to the invention may be carried out as continuous orbatchwise processes. Processes for carrying out catalytic reactions aredescribed in the literature and adequately known to those skilled in theart.

Optionally, the process according to the invention may be carried outduring the reaction to be catalyzed by the complex (1).

It is therefore possible to prepare the metal complexes (I) in situ fromthe compounds II to X and one of the metals mentioned as catalysts inhydroformylations, hydrogenations, aryl aminations, hydrosilylations,Heck reactions, Suzuki couplings, Kumada couplings, Stille couplings,Miyaura couplings, Sonogashira couplings, olefin metatheses, olefindimerization, olefin oligomerizations, cyclopropanations, reduction ofhaloarenes, polymerizations or telomerization reactions, or they may beused as a catalyst in these reactions.

Based on R. Jackstell, M. Gómez Andreu, A. Frisch, K. Selvakumar, A.Zapf, H. Klein, A. Spannenberg, D. Röttger, O. Briel, R. Karch, M.Beller, Angewandte Chemie 2002, 114, 128, in the context of thisinvention, telomerization refers generally to the reaction of olefinshaving conjugated double bonds (conjugated dienes) in the presence of anucleophile (telogen). The main products obtained are compounds whichare formed from two equivalents of the diene and one equivalent of thenucleophile. The telomerization of dienes is described comprehensivelyin the technical literature (WO 91/09822, U.S. Pat. No. 4,642,392, U.S.Pat. No. 4,831,183, DE 2 137 291, U.S. Pat. No. 5,030,792, U.S. Pat. No.4,334,117, U.S. Pat. No. 4,356,333, U.S. Pat. No. 5,057,631, EP 0 296550, WO 98/08 794, DE 195 23 335).

The products of the telomerization reaction have industrial significanceas versatile precursors for solvents, plasticizers, fine chemicals andactive ingredient precursors. Octadienol, octadienyl ethers oroctadienyl esters, obtainable from 1,3-butadiene, are potentialintermediates in processes for preparing corresponding alkenes.

The telomerization of dienes with nucleophiles is a method of industrialinterest for upgrading inexpensive, industrially available dienes. Owingto the good availability, the use of butadiene, isoprene or cracker cutscomprising these dienes is of particular interest. To date, thetelomerization of 1,3-butadiene is, however, employed practically onlyby Kuraray in the fine chemicals field for the synthesis of 1-octanol.Reasons which prevent wider use of telomerization processes includeinadequate catalyst activities, catalyst productivities and selectivityproblems of telomerization catalysts. Thus, the known telomerizationprocesses lead to high catalyst costs and/or by-products which preventindustrial scale realization.

The catalysts used mainly have palladium as the central atom andphosphorus ligands. These catalysts afford, for example, in thetelomerization of butadiene with methanol, generally mixtures of theproducts 1a, 1b, 2, 3 shown. Main products are the desired industriallyimportant linear telomers 1a and 1b. However, significant proportions ofthe branched telomer 2 and of 1,3,7-octatriene 3 are formed.

In addition, 4-vinyl-1-cyclohexene (Diels-Alder product of butadiene) isformed in variable yields, and also, generally in only small amounts,further by-products. This spectrum of products is found generally alsowhen other nucleophiles having active hydrogen atoms are used, in whichcase the corresponding radicals of the particular nucleophile occur inplace of the methoxy group.

The significant formation of the by-products mentioned is a furtherreason which makes an implementation of an economically viable andenvironmentally friendly process extremely difficult. Even though thetelomerization of butadiene with methanol has already been intensivelyresearched and patented by several companies, it has not been possibleto satisfactorily solve the abovementioned problems.

The use of the complexes prepared in accordance with the invention ascatalysts or catalyst precursors in the telomerization of noncyclicolefins having at least two conjugated double bonds (XII) with anucleophile (XIII) can achieve distinct improvements in theselectivities.

In the telomerization in the process according to the invention, it ispossible in principle to use all noncyclic olefins having at least twoconjugated double bonds. In the context of this invention, preference isgiven to using 1,3-butadiene and isoprene (2-methyl-1,3-butadiene). Itis possible to use either the pure dienes or mixtures which comprisethese dienes.

The 1,3-butadiene/isoprene-containing mixtures used are preferablymixtures of 1,3-butadiene or isoprene with other C₄ hydrocarbons and/orC₅ hydrocarbons. Such mixtures are obtained, for example, in crackingprocesses for the production of ethene, in which refinery gases,naphtha, gas oil, LPG (liquefied petroleum gas), NGL (natural gasliquid), etc. are converted. The C₄ cuts obtained as a by-product inthese processes contain different amounts of 1,3-butadiene depending onthe cracking process. Typical 1,3-butadiene concentrations in the C₄cut, as obtained from a naphtha steam cracker, are 20-70% 1,3-butadiene.

The C₄ components n-butane, i-butane, 1-butene, cis-2-butene,trans-2-butene and i-butene, which are likewise present in these cuts,only insignificantly disrupt the reaction in the telomerization step, ifat all.

In contrast, alkynes, especially vinylacetylene, can act as moderatorsin the telomerization reaction. It is therefore advantageous to removethe C4 alkynes and optionally also cumulenes such as 1,2-butadienebeforehand (for example according to DE 195 23 335). This may, ifpossible, be effected by physical processes such as distillation orextraction. By a chemical route, the alkynes may be reduced to alkenesor alkanes by selective hydrogenations, and the accumulated dienesreduced to monoenes. Processes for such hydrations are prior art and aredescribed, for example, in WO 98/12160, EP-A-0 273 900, DE-A-37 44 086or U.S. Pat. No. 4,704,492.

The nucleophiles (XIII) used are preferably

-   water,-   alcohols and phenols, for example methanol, ethanol, n-propanol,    isopropanol, allyl alcohol, butanol, octanol, 2-ethylhexanol,    isononanol, benzyl alcohol, cyclohexanol, cyclopentanol,    2-methoxyethanol, phenol or 2,7-octadien-1-ol-   dialcohols, for example ethylene glycol, 1,2-propanediol,    1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 2,3-butanediol and    1,3-butanediol-   polyols, for example glycerol, glucose, sucrose,-   hydroxy compounds, for example α-hydroxyacetic esters-   carboxylic acids, for example acetic acid, propanoic acid, butanoic    acid, isobutanoic acid, benzoic acid, 1,2-benzenedicarboxylic acid,    1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid,    1,2,4-benzenetricarboxylic acid, ammonia, primary amines, for    example methylamine, ethylamine, propylamine, butylamine,    octylamine, 2,7-octadienylamine, dodecylamine, aniline,    ethylenediamine or hexamethylenediamine, secondary amines such as    dimethylamine, diethylamine, N-methylaniline,    bis(2,7-octadienyl)amine, dicyclohexylamine, methylcyclohexylamine,    pyrrolidine, piperidine, morpholine, piperazine or    hexamethyleneimine.

Telogens which can themselves be obtained by a telomerization reactionmay be used directly or else formed in situ. For example,2,7-octadien-1-ol can be formed in situ from water and butadiene in thepresence of the telomerization catalyst, 2,7-octadienylamine fromammonia and 1,3-butadiene, etc.

Nucleophiles (XIII) used with particular preference are water, methanol,ethanol, n-butanol, allyl alcohol, 2-methoxyethanol, phenol, ethyleneglycol, 1,3-propanediol, glycerol, glucose, sucrose, acetic acid,butanoic acid, 1,2-benzenedicarboxylic acid, ammonia, dimethylamine anddiethylamine.

The telomerization is preferably carried out in the presence of asolvent. The solvent used is generally the nucleophile used when it ispresent as a liquid under reaction conditions. However, it is alsopossible to use other solvents. The solvents used should besubstantially inert. Preference is given to adding solvents whennucleophiles are used which are present as solids under reactionconditions, or in the case of products which would be obtained as solidsunder the reaction conditions. Suitable solvents include aliphatic,cycloaliphatic and aromatic hydrocarbons, for example C₃-C₂₀-alkanes,mixtures of lower alkanes (C₃-C₂₀), cyclohexane, cyclooctane,ethylcyclohexane, alkenes and polyenes, vinylcyclohexene,1,3,7-octatriene, the C₄ hydrocarbons from C₄ cuts from crackers,benzene, toluene and xylene; polar solvents, for example tertiary andsecondary alcohols, amides, for example acetamide, dimethylacetamide anddimethylformamide, nitriles, for example acetonitrile and benzonitrile,ketones, for example acetone, methyl isobutyl ketone and diethyl ketone;carboxylic esters, for example ethyl acetate, ethers, for exampledipropyl ether, MTBE, diethyl ether, dimethyl ether, methyl octyl ether,3-methoxyoctane, dioxane, tetrahydrofuran, anisole, alkyl and arylethers of ethylene glycol, diethylene glycol and polyethylene glycol,and other polar solvents, for example sulfolane, dimethyl sulfoxide,ethylene carbonate, propylene carbonate and water. Ionic liquids too,for example imidazolium or pyridinium salts, may be used as solvents.The solvents may be used alone or as mixtures of different solvents ornucleophiles.

The temperature at which the telomerization reaction is performed ispreferably between 10 and 180° C., in particular between 30 and 120° C.,more preferably between 40 and 100° C. The reaction pressure is from 1to 125 bar, preferably from 1 to 64 bar, more preferably from 1 to 26bar.

Metal compounds (II) used with preference in the telomerization aresalts or complexes of palladium, for example palladium(II) acetate,palladium(II) chloride, palladium(II) bromide, lithiumtetrachloropalladate, palladium(II) acetylacetonate,palladium(0)-dibenzylideneacetone complexes, palladium(II) propionate,bis(acetonitrile)palladium(II) chloride,bis(triphenylphosphine)palladium(II) dichloride,bis(benzonitrile)palladium(II) chloride,bis(tri-o-tolylphosphine)palladium(0).

The concentration of the catalyst in the telomerization reaction,reported formally in ppm (by mass) of catalyst metal based on the totalmass, is from 0.01 ppm to 1000 ppm, preferably from 0.5 to 100 ppm, morepreferably from 1 to 50 ppm.

When the catalyst for the telomerization is prepared in situ from ametal compound and a ligand precursor of the general formulae (II) to(X), the ligand precursor is preferably used in a ratio [mol/mol] ofligand precursor to metal of from 100:1 to 1:1, more preferably from10:1 to 1:1.

Additional ligand precursor may be introduced into the process at anytime in the reaction. Further ligands, for example phosphorus ligandssuch as triphenylphosphine, may likewise be present in the reactionmixture.

Owing to the catalyst activities and stabilities, it is possible in thetelomerization to use extremely small amounts of catalyst. In additionto a process in which the catalyst is reused, the option is thus alsoopened up of not recycling the catalyst. Both variants have already beendescribed in the patent literature (WO 90/13531, U.S. Pat. No.5,254,782, U.S. Pat. No. 4,642,392).

It is often advantageous to carry out the telomerization reaction in thepresence of bases. Preference is given to using basic components havinga pK_(b) of less than 7, especially compounds selected from the group ofamines, alkali metal salts, alkaline earth metal salts, alkoxides andphenoxides.

Suitable basic components are, for example, amines such astrialkylamines which may be alicyclic or/and open-chain, amides, alkalimetal or/and alkaline earth metal salts of aliphatic or/and aromaticcarboxylic acids such as acetates, propionates, benzoates orcorresponding carbonates, hydrogencarbonates, alkoxides of alkali and/oralkaline earth elements, phosphates, hydrogenphosphates or/andhydroxides, preferably of lithium, sodium, potassium, calcium,magnesium, cesium, ammonium and phosphonium compounds. Preferredadditives are hydroxides, alkoxides and phenoxides of the alkali andalkaline earth elements.

In general, the basic component is used in the telomerization reactionbetween 0.01 mol % and 10 mol % (based on the olefin), preferablybetween 0.1 mol % and 5 mol % and most preferably between 0.2 mol % and1 mol %. The ratio [mol/mol] between diene and nucleophile used is from1:1000 to 100:1, preferably from 1:50 to 10:1, more preferably from 1:10to 2:1.

The process for telomerization using the complexes prepared inaccordance with the invention as catalysts or catalyst precursors may beoperated continuously or batchwise, and is not restricted to the use ofcertain reactor types. Examples of reactors in which the reaction can becarried out are stirred tank reactors, stirred tank batteries, flowtubes and loop reactors. Combinations of different reactors are alsopossible, for example a stirred tank reactor with downstream flow tube.

The catalysts employed for metathesis reactions are often complexes ofosmium and in particular of ruthenium. It has been possible in recenttimes to obtain novel catalysts having improved properties fromcomplexes which have phosphine ligands and are known in principle byintroducing heterocyclic carbene ligands. In addition to the use ofmetal complexes of defined structure, methods for the in situpreparation of metathesis-active catalysts have also been described (WO0058322, DE 19815275, EP 1022282, WO 0071554, WO 0220535).

In the process according to the invention, metathesis-active metalcomplexes are obtained by reacting metal compounds with ligandprecursors according to the general formulae (II) to (X).

The catalysts are suitable for ROMP (ring-opening metathesispolymerization), RCM (ring-closing metathesis) and ADMET (acyclic dienemetathesis). The metal compounds used are preferably compounds ofruthenium.

1. A process for preparing complexes of metals of groups 6 to 10 of thePeriodic Table of the Elements by reacting a compound of a metal ofgroups 6 to 10 of the Periodic Table of the Elements with compounds ofthe formula II and/or III

where R¹, R², R³, R⁴ are the same or different and are each linear,branched, substituted or unsubstituted, cyclic or alicyclic alkyl groupshaving from 1 to 24 carbon atoms; substituted or unsubstituted, mono- orpolycyclic aryl groups having from 6 to 24 carbon atoms; mono- orpolycyclic, substituted or unsubstituted heterocycles having from 2 to24 carbon atoms; a heteroatom from the group of N, O, S, and R³, R⁴ mayhave a covalent bond R⁵, R⁶, R⁷ may be the same or different and mayeach be H, linear, branched, substituted or unsubstituted, cyclic oralicyclic alkyl groups having from 1 to 24 carbon atoms; substituted orunsubstituted, mono- or polycyclic aryl groups having from 6 to 24carbon atoms, with the proviso that the R⁷ substituent is not H.
 2. Theprocess as claimed in claim 1, wherein the compounds of the formulae IIor III used are compounds of the general formulae V to X

where R¹, R², R⁵, R⁶, R⁷ are each as defined above and R⁸, R⁹, R¹⁰, R¹¹are the same or different and are each H or have one of the definitionsof R¹.
 3. The process as claimed in claim 1, wherein complexes of thegeneral formula I

are prepared where [Z] is a metal complex fragment of the generalformula[L_(a)M_(b)][A]_(n)  (XI) and M is: metal of groups 6 to 10 of thePeriodic Table of the Elements L is: one or more identical or differentmono- or polydentate, charged or uncharged ligands A is: a singlycharged anion or the chemical equivalent of a multiply charged anion, bis: an integer of from 1 to 3 a is: an integer of from 0 to 5×b n is: aninteger from 0 to 6 and R¹, R², R³, R⁴ are each defined as specified. 4.The process as claimed in claim 3, wherein L in the general formula (XI)is hydrogen, the hydrogen ion, halogens, halogen ions, pseudohalides,carboxylate ions, sulfonate ions, amide radicals, alkyl groups,alkylaryl groups, aryl groups, heteroaryl groups, alkenyl groups,alkenyl groups, alkoxide radicals, nitriles, isonitriles, mono- ordiolefins, alkynes, 1-aromatic radicals, cyclopentadienyl, indenyl,phosphines, phosphites, phosphinites, phosphonites, phosphorusaromatics, acetylacetonate, carbon monoxide, nitrogen monoxide orcarbene ligands, where the alkyl groups contain from 1 to 24, thealkenyl and heteroaryl groups from 2 to 24, and the aryl and alkylarylgroups from 5 to 24, carbon atoms, and may each be substituted orunsubstituted.
 5. The process as claimed in claim 3, wherein A in thegeneral formula (XI) is halide, pseudohalide, tetraphenylborate,tetrafluoroborate, tetrachloroborate, hexafluorophosphate,hexafluoroantimonate, tetracarbonylcobaltate, hexafluoroferrate,tetrachloroferrate, tetrachloroaluminate, triflate,bistrifluorosulfonylamide, heptachlorodialuminate, tetrachloropalladate,sulfate, hydrogensulfate, nitrate, nitrite, phosphate,hydrogenphosphate, dihydrogenphosphate, hydroxide, carbonate,hydrogencarbonate, salts of aromatic or aliphatic carboxylic acids,salts of aromatic or aliphatic sulfonic acids or phenoxides.
 6. Theprocess as claimed in claim 1, wherein the metal of groups 6 to 10 ofthe Periodic Table which is used is Ru, Rh, Ni, Pd or Pt.
 7. The processas claimed in claim 1, wherein the metal complexes (I) are prepared fromthe compounds II to X and a metal of groups 6 to 10 of the PeriodicTable in situ as catalysts or catalyst precursors in hydroformylations,hydrogenations, aryl aminations, hydrosilylations, Heck reactions,Suzuki couplings, Kumada couplings, Stille couplings, Miyaura couplings,Sonogashira couplings, olefin metatheses, cyclopropanations, reductionof haloarenes, polymerizations or telomerization reactions.
 8. Theprocess as claimed in claim 1, wherein one or more of the compounds IIto X is used in a ratio of from 1 to 100 mol to the metal of groups 6 to10 of the Periodic Table.
 9. The use of the compounds II and/or III asligand precursors in hydroformylations, hydrogenations, aryl aminations,hydrosilylations, Heck reactions, Suzuki couplings, Kumada couplings,Stille couplings, Miyaura couplings, Sonogashira couplings, olefinmetatheses, cyclopropanations, reduction of haloarenes, polymerizationsor telomerization reactions.